The present invention relates to a process for producing a (meth)allyl ester monomer having an alicyclic structure within the molecule (hereinafter simply referred to as an xe2x80x9calicyclic (meth)allyl ester monomerxe2x80x9d) by transesterification of an alkyl ester of a polybasic acid having an alicyclic structure with a (meth)allyl ester, a process for producing an alicyclic (meth)allyl ester compound using an alicyclic (meth)allyl ester monomer produced by the above-described process and a polyhydric alcohol as starting materials, and an alicyclic (meth)allyl ester compound produced by this process.
The present invention also relates to a plastic lens composition containing the above-described alicyclic (meth)allyl ester compound, a plastic lens obtained by curing the composition, and a process for producing the plastic lens.
Still further, the present invention relates to a plastic lens composition comprising an alicyclic (meth)allyl ester compound, which can be used to produce a plastic lens while inhibiting generation of uneven dyeing and at the same time, preventing a mold from being damaged; a plastic lens obtained by curing the composition; and a process for producing the plastic lens.
The term xe2x80x9c(meth)allyl alcoholxe2x80x9d as used herein refers to an allyl alcohol, a methallyl alcohol and/or a mixture thereof. The term xe2x80x9c(meth)allyl ester monomerxe2x80x9d as used herein refers to an allyl ester monomer, a methallyl ester monomer and/or a mixture thereof. The term xe2x80x9c(meth)allyl ester compoundxe2x80x9d as used herein refers to an allyl ester compound, a methallyl ester compound and/or a mixture thereof.
The alicyclic (meth)allyl ester monomer produced by reacting an alkyl ester of a polybasic acid having an alicyclic structure with an allyl alcohol or a methallyl alcohol is a highly reactive monomer. This monomer is used with various crosslinking agents or reactive diluting agents and the polymer of the monomer itself is widely used for various molded articles, laminates, decorative sheets and the like because of its excellent electrical properties, dimensional stability, heat resistance, weather resistance, chemical resistance and mechanical properties. In recent years, the polymer has also been found to have excellent optical properties and the use thereof as an optical material has begun.
The polyethylene glycol bis(allyl carbonate) resin which has been heretofore used is low in its polymerization reaction rate as compared with the acrylic resin, therefore, the polymerization reaction thereof is easy to control. As a result, a uniform polymerization reaction can be attained and the plastic lens derived from the polyethylene glycol bis(allyl carbonate) resin is advantageously small in the optical strain.
With respect to the dyeability of a plastic lens derived from the polyethylene glycol bis(allyl carbonate) resin, in the case where a plastic lens obtained by cast molding is dyed by the general means of dipping the lens in a dye bath at a high temperature, the dyeing density is known to be excellent as compared with plastic lenses derived from other resins.
However, the polydiethylene glycol bis(allyl carbonate) resin has a problem in that when a plastic lens derived from the resin is dyed, uneven dyeing is generated.
In order to overcome this problem, International Patent Publication Nos. WO99/17137 and WO99/38899 discloses use of an allyl ester compound containing a polycarboxylate structure having an alicyclic structure. In these publications, it is stated that uniform dyeing, which is required for the dyeability of plastic lens, can be attained, namely, an improved effect is provided on the reduction of uneven dyeing.
However, depending on the production process of an allyl ester monomer as a starting material, the above-described allyl ester compound sometimes fails in satisfying the requirement for long-term storage stability of the composition for optical materials represented by a lens.
Known examples of the production process for this kind of allyl ester monomer or methallyl ester monomer include:
1) a synthesis method starting from carboxylic acid chloride and an alcohol;
2) a synthesis method starting from an alkali salt of carboxylic acid and an alkyl halide; and
3) a synthesis method starting from carboxylic acid and an alcohol.
However, use of these methods in the production of compounds related to the present invention has a problem in that in the method 1), the acid chloride as a starting material is expensive.
In the case of applying the method 2), a side reaction of hydrolyzing the alkyl halide into a (meth)allyl alcohol takes place in a fairly high ratio and the operation of separating or recovering the starting materials and the by-product is disadvantageously complicated and costly.
In the method 3), a strong acid catalyst is generally used but the (meth)allyl alcohol is not stable to an acid catalyst usually used and has a problem in that di(meth)allyl ether is produced as a by-product. In addition to the low yield of (meth)allyl alcohol, it has been found that when sulfuric acid or p-toluenesulfonic acid is used as a catalyst, a corresponding allyl ester is produced as the by-product of the catalyst and these allyl sulfonate esters are difficult to separate from the objective alicyclic (meth)allyl ester monomer and in turn, the product is relatively low in the stability during a long-term storage and cannot cope with the use where the product is required to have a long-term storage stability, such as a composition for optical material use.
In this specification, the term xe2x80x9cdi(meth)allyl etherxe2x80x9d refers to a diallyl ether, a dimethallyl ether and/or a mixture thereof.
By taking account of these problems in conventional techniques, it is an object of the present invention to provide a process for producing an alicyclic (meth)allyl ester monomer, comprising reacting an alkyl ester of a polybasic acid having an alicyclic structure, which has heretofore not been used as a starting material of the alicyclic (meth)allyl ester monomer, with a (meth)allyl alcohol in the presence of a transesterification catalyst, a process for producing an alicyclic (meth)allyl ester compound having a (meth)allyl ester group at the terminal, using the alicyclic (meth)allyl ester monomer, and the alicyclic (meth)allyl ester compound.
It is another object of the present invention to provide a plastic lens composition comprising the alicyclic (meth)allyl ester compound, which is suitable for the production of optical materials, particularly, a plastic lens, a plastic lens obtained by curing the plastic lens composition, and a process for producing the plastic lens.
As a result of extensive investigations to solve the above-described problems, the present inventors have found that, when a lower aliphatic alkyl ester of a polybasic acid having an alicyclic structure and a (meth)allyl alcohol are reacted by transesterification while distilling out a lower aliphatic alcohol, the objective alicyclic (meth)allyl ester monomer can be produced. Furthermore, it has been found that an alicyclic (meth)allyl ester compound having a (meth)allyl ester group at the molecular terminal can be produced using the alicyclic (meth)allyl ester monomer by a transesterification reaction with a polyhydric alcohol and also that this alicyclic (meth)allyl ester compound can be suitably used for optical use. The present invention has been accomplished based on these findings.
More specifically, the present invention (I) is a process for producing an alicyclic (meth)allyl ester monomer, comprising reacting an alkyl ester of a polybasic acid having an alicyclic structure with an allyl alcohol and/or a methallyl alcohol in the presence of a transesterification catalyst.
The present invention (II) is a process for producing an alicyclic (meth)allyl ester compound having a terminal structure of formula (1) and a repeating unit of formula (2), comprising transesterifying an alicyclic (meth)allyl ester monomer produced by the present invention (I) with a polyhydric alcohol in the presence of a catalyst. The present invention (II) includes an alicyclic (meth)allyl ester compound having a terminal structure of formula (1) and a repeating unit of formula (2), which is produced by the production process. 
wherein each R1 independently represents an allyl group or a methallyl group, each X independently represents an organic residue derived from a polyvalent carboxylic acid having an alicyclic structure, and each Y independently represents an organic residue derived from a polyhydric alcohol having from 2 to 20 carbon atoms and containing from 2 to 6 hydroxyl groups, provided that, by the ester bonding, X may have a branched structure having a terminal group of formula (1) and a repeating unit of formula (2) or may have R1, and that by the ester bonding, Y may have a branched structure having a terminal group of formula (1) and a repeating unit of formula (2).
The present invention ,(III) is a plastic lens composition comprising an alicyclic (meth)allyl ester compound of the present invention (II).
The present invention (IV) is a plastic lens composition comprising at least one radical polymerization initiator in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the entire curable component contained in the plastic lens composition.
The present invention (V) is a plastic resin obtained by curing the plastic lens composition of the present invention (III) or (IV).
The present invention (VI) is a process for producing the plastic lens of the present invention (V).